Recently, as an electronic device becomes small and slim, such as a portable terminal including a mobile phone and a notebook computer becoming slim to have a thickness in a level of several mm, a technology for refining a copper circuit pattern of a PCB has been demanded.
In the related art, in order to form a solder on pad on a metal pad of a PCB, a metal mask for a screen printer having a shape matched one-to-one with each metal pad is manufactured, and then a solder paste is applied only to a metal pad portion.
In such a case, when a pitch of the metal pad is 130 μm or less, a spreading property of the solder paste from a mask is deteriorated, so that it is difficult to evenly apply a predetermined quantity of solder paste on the metal pad.